Resistance welding electrode with guide pin

Abstract

In an electrode for welding with a retractable guide pin so received in a guide hole of the electrode that air blows out from a gap between the guide hole and the guide pin as the guide pin is pushed in to prevent intervention of foreign matters between an end face of an electrode and a steel sheet part or at a sliding portion of the guide pin, a large-diameter hole (33) and a small-diameter hole (34) are provided at a portion through which passes a small-diameter portion (7) of the guide pin (6) so as to form a receiving face (35) with the difference in diameter between the two, and an exhaust passage is provided near the receiving face (35) to establish communication between the large-diameter hole (33) and outside of the electrode.

We claim: 
     
       1. An electrode for welding in which a guide pin inserted in a guide hole of the electrode in a way to be movable forward and backward is composed of a large-diameter portion sliding in the guide hole and a small-diameter portion protruding from the electrode and that air blows out from the outer circumference of the guide pin as the guide pin is pushed in, characterized in that the guide hole has a first large-diameter bore through which passes the large-diameter portion and a second bore through which passes the small-diameter portion, that the second bore is composed of a large-diameter hole and a small-diameter hole adjacent the first bore, and that a discharge passage communicating between the large-diameter hole and the outside of the electrode is radially formed in the electrode. 
     
     
       2. An electrode for welding according to claim 1, wherein an annular receiving surface is formed between the large-diameter hole and the small-diameter hole on a side away from the first bore by using the difference in inside diameter between the large-diameter hole and the small-diameter hole and an inner end of the discharge passage is disposed adjacently to the receiving surface to cause foreign matters coming in the large-diameter hole to hit the receiving surface so that the foreign matters are carried outside the electrode by means of an air current from the small-diameter hole through the discharge passage. 
     
     
       3. An electrode for welding according to claim 1, wherein the small-diameter portion of the guide pin is slidably received in the small diameter hole with a slight amount of gap therebetween, thereby ensuring that the guide pin is supported at substantially two points. 
     
     
       4. An electrode for welding according to claim 1, wherein the guide pin is made of metal at its small-diameter portion and of a synthetic resin at its large-diameter portion, and wherein the small-diameter hole through which passes the small-diameter portion is formed in a synthetic resin member. 
     
     
       5. An electrode for welding with guide pin in which a guide pin inserted in a guide hole of the electrode in a way to be movable forward and backward is composed of a large-diameter portion sliding in the guide hole and a small-diameter portion protruding from the electrode and positioning a counterpart, characterized in that the guide hole has a first large-diameter bore through which passes the large-diameter portion and a second bore through which passes the small-diameter portion, that the second bore is composed of a large-diameter hole and a small-diameter hole adjacent the first bore, and that a ring-shaped receiving face is formed between the large-diameter hole and the small-diameter hole on a side away from the first bore by using the difference in inside diameter between the large-diameter hole and the small-diameter hole.